Introduction: Simple Cheap VU Meter

Basically, a while ago I wanted to make a VU meter (because they are awesome).
I went through multiple designs, and this one was the one that I liked the most. So far, I have not found any other VU circuit as simple as this. If you find one, show me!

First of all, the parts...

Some PCB (if you can get those fiberglass PCBs, LEDs look so much cooler in more transparent PCB)

10xBlue SMD LEDs (specific one in the pictures)

1xLM3914/3915/3916

2x3.5mm Audio plug

1x3.5mm Audio plug male-male ends

5v power source (USB, battery, etc.)

Clear nail polish

2 pin header (for 5v power)

Here is a video of an older version of the VU meter (I have three versions). You might like this design better?

Step 1: Design and Parts Continued

I did not mention that you needed resistors. In the photo I have resistors: the function of them is to scale down the current going from input to output audio plugs.

In order for the VU meter to be simple as possible and run on 5v (rather than most projects at 6v), I did not include an amplifier circuit. Instead, you will have to turn up your music a little higher for the VU meter to respond. The resistors will serve to lower that volume to what you want it to be when you listen to it.
I would use a resistance from 200-400 ohms. Remember that this is a resistor, and not a voltage divider.

Okay, so attached is a simple schematic, and the design. Download this awesome free PCB software to view the file!
Remember to print BLACK ink, HIGH quality, ACTUAL SIZE.

Step 2: Exposure

Now that it is cut, quickly peel off the protective layer, align the transparency onto the board (please note that I added text on the copper so that you will know how to orient the transparency), put a piece of plexiglass to flatten the sheets, and place a lamp on top of the sandwich.

Do this quickly, but it's ok if you are a bit slow: get it right the first time.

side note
Recently, all my drill bits have been breaking like crazy. This really put a damper on my projects. I bought a bunch of new drill bits and I reccomend steel drill bits. They drill extremely quickly.
I'm not sure if this link will work in the next week, month, or year, but here it is.

After drilling, sand out the edges.
After sanding, prepare tweezers and your LEDs.
For these LEDs, the side with the notch is the negative end.
Solder one pad of all the LEDs on the PCB.

Step 6:

So, now that your board is finished, test it out on your audio player!

From my previous VU meter versions, I used USB power which worked perfectly. Recently I discovered that I can also power it from this battery from this project.
What's really cool is that you can pair up these two devices and have an awesome audio player!

So, once you verify that it works, you want to make it last,
so clean the PCB with alcohol to remove ugly goop from flux, and cover it in glossy clear nail polish.